Machine gun bolt mechanism



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INVENTOR' BY ,my www@ ATTORNEY HIII 5 Sheets-Shea?I 5 R MENDOZA MACHINE GUN BOLT MEGHANISM Filed oct. 1`, 1954 Febi 1s, 1936.

ATTOR N EY WITN EBS:

Patented Feb. 18, 1936 UNITED STATES PATENT 'OFFICE 2,031,383 MACHINE GUN BoL'r MECHANISM Rafael Mendoza, Mexico, D. F., Mexico Application October 1, 1934, Serial No. 746,445

5 Claims.

This invention relates to automatic firearms and more particularly an improved means for' releasably securing the gun barrel to the case or frame of thev gun and which, when in securingo position, will effectively prevent` relative movements between said parts.

lll/"1th these and other objects in view, this invention consists in certain novel features of construction, combination and. arrangement of parts to be hereinafter more fully described and claimed.

For a complete understanding of my invention, reference is to be had to the following description and accompanying drawings, in which Figure 1 is a fragmentary longitudinal sectional view illustrating an automatic rearm 'constructedin accordance with my invention.

Figure 2 isa fragmentary detail view showing the securing means for effectively and removably securing the gun barrel to the gun frame or case.

Figure 3 is a perspective-view illustrating a portion of the gun case `or frame.

Figure 4 is a perspective view illustrating the magazine. p

Figure 5 is a fragmentary vertical sectional view showing the connection between the magazineA and the gun case or frame.

Figure 6 is a transverse sectional on the line 6--6 of Figure 1.

Figure 7 is a horizontal sectional view showing the partial ejection of a i'lred shell from the gun.

Figure 8 is a similar View showing the com` plete ejection of the fired shell.

Figure 9 is a fragmentary vertical sectional view showing the ring of a shell and the utilization of' the explosive charge to return the bolt and firing vpin to cocked or ring position.

Figure 10 is a. fragmentary horizontal sectional view illustrating automatic means for temporarily holding the bolt in ring position on the exhaustion of ammunition in thesm'agazine and gun.

Figure 11 is an enlarged fragmentary horizontal sectional view showing the bolt and firing pin in firing position and also showing the locking means between the barrel and the gun frame or case.

Figure 12 is a transverse sectional view taken on the line I24-I2 of Figure 1.

Figure 13 is a fragmentary view, partly in section, showing the trigger and sear of the gun set for semi-automatic firing.

Figure 14 is a perspective view illustrating the lever for temporarily holding the bolt in cocked view taken position after the exhaustion of ammunition from the gun and magazine.

Figure 15 is a perspective view bolt. y

Figure 16 is a perspective view illustrating an ejector dog carried by the bolt.

Figure 17 is a perspective view illustrating the ring pin.

Referring iu detail toy th drawings, the numeral I indicates a gun barrel equipped with a 10 ring chamber 2 'in one endv thereof and which endis removably secured to a gun case or frame 3, the latter having a chamber .4 to slidably support a bolt 5 in which is slidably mounted a ring pin 6, either end of which may be employed for 15 striking the capO of the shell by moving 'for a hunted distance through an opening 1 provided in the end of the bolt. The end. of the barrel which is releasably secured to the gun 'frame or case is provided with a tapered groove ilA to receive 2o a tapered wedge 9 and the latter is pivotally and slidably connected to a lever III. A pin and slot connection is provided between the wedge and the lever and the pivoted end of said lever has a cam face II and a shoulder I2 adapted to abut 25 a shoulder I3 onthe gun case or frame when vthe lever is in wedge securing position. A- slot I 4 is provided in the gun case or frame and presents an undercut shoulder I5 to be engaged by a catch I6 rigidly secured to a nger'piece I1 mounted for a 30 limited sliding movement on the lever I0. The catch I6l when in engagement with the shoulder I5 -retains the lever against pivotal movement and with the shoulder I2 in abutting engagement with the shoulder i3. A leaf spring I8 is arranged 35 in the lever Il), one end of which bears against the outer end of the wedge 9 and the opposite end uiustraungthe is offset to act on the sleeve or nger piece I1 for retaining the catch I6 in engagement with the shoulder I5. The last-named end of the spring 40 latter in the groove of the gun barrel so that said A wedge may be easily drawn from the groove of the gun barrel and the groove provided in the gun-\ case or frame whence the barrel may be detached from` the gun case or frame. The -parts as positioned inf Figure 11, the i I8 f" 55 against the end of the wedge acts .to urge said wedge tightly against the walls of the groove in the barrel andY gun case or frame and thereby effectively secure the gun barrel and gun case or frame from having relative movement.

A magazine chamber I9 is formed in one side of the gun case or frame and at one end opens outwardly through the top face of the gun case or frame and the opposite end is communicative with the chamber 4. A magazine 20 is removably secured ln the magazine chamber I9 with its outlet end 2| positioned to direct a shell partially into the chamber 4. The magazine is arcuately curved and extends upwardly and forwardly with respect to the gun, the mouth of the magazine being confined in the magazine chamber and formed by an arcuately curved flange aiding in directing the shell partially into the chamber 4. It is to be understood that the magazine is loaded with shells from the mouth and .operating in the magazine is a follower 22, operating against the action of a spring 23 and equipped at one end with a projection 23 confined within the magazine as long as a shell remains in the magazine and on the exhaustion of the shells from the magazine the projection is adapted to extend through a slot 24 in the magazine adjacent the mouth. A rib 25 is formed on the follower and is disposed at an inclination to engage with a stop or pin 26 on the magazine as the follower aligns with the slot 24 to cause an endwise movement of the follower suflicient lto extend the projection 23 a distance outwardly of the magazine. A shoulder 21 is provided on the opposite side of the magazine from the slot -24 and is adapted to t under a shoulder 28 formed on a wall of the magazine chamber I9 adjacent to where said magazine chamber opens outwardly through the top face of the gun frame or case. A projection 29 is formed on the opposite side of the magazine from the projection 21 and when the magazine is inserted in the magazine chamber the projection 29 engages with a spring pressed plunger 30 carried by the gun case or frame. The plunger 30 acts to slide the magazine in the chamber endwise of the gun to bring the projection 21 under the shoulder 28, suicient clearance being provided in the chamber for permitting a limited sliding movement of the magazine in the chamber endwise ofthe gun. To remove the magazine from the chamber, the 4latter is slid endwise of the gun, the plunger 30 yielding to permit the projection 21 to move from under the shoulder 28 and when in this position the magazine may be readily withdrawn from the magazine chamber. The purpose of the extension 23' on the follower 22 is to bring about positioning of a locking lever 3| to retain the bolt in firing position on the exhaustion of shells from the magazine. The lever is pivoted to the gun case or frame, as shown at 32, andadjacent one end is provided with a shoulder 33 adapted to be brought into engagement with a shoulder 34 formed on the bolt by an opposite end '35 of said lever riding upon an inclined face 38 located at the other end of the bolt. 'I'he end 35 of thelever is engaged by the face 36 on the bolt moving into cocked position consequently bringing the shoulder 33 in engagement with; the face 34 but as the lever is pivotally mounted and the shoulder 33 and face 34 so shaped the bolt when driven or released from cocked position may move into ring position. However, as the last shell is fed into the barrel of the gun and the magazine -is exhausted of shells the projection 23' engages with the lever and prevents pivotal movement thereof so that the shoulder 33 engaging the face 34 will retain the bolt in cocked position until such time the magazine is removed from the magazine chamber I9. This arrangement is provided so that the bolt will not be released from firing position by the operator when the shells are exhausted from the magazine and gun keeping the bolt in cocked position ready to actuate on the introduction of another magazine filled with shells,

The gun case or frame is equipped with a shell discharge slot 31 in one side thereof and this slot communicates with the chamber 4 substantially opposite to the communication of the magazine chamber with said chamber 4. The walls of the chamber 4 are. provided with longitudinally extending grooves 38 in which operate lugs 39 on the bolt 5 and which permit the bolt 5 to have free sliding movement in the chamber either from cocked to firing position or from the latter-named position to cocked position. Arranged at rightY angles to the 'grooves 38 are grooves 48 and are in communication with the grooves 38 to permit a limited rotation of the bolt as the latter reaches firing position, the lugs entering said grooves 40. Oppositely arranged slots 4| are provided in the bolt and the ring pin 6 has a slot 42 aligning with said slots 4|. through the slot 42 into the other slot 4| is a projection or arm 43 secured to a plunger 44 forming a part of.-a combined firing and cocking mechanism which will be hereinafter more fully described. Opposite walls of each slot 4| are Extending through one of the slots 4| and provide to each slot portions A and B one disposed slightly laterally of the other. The bolt when in cocked position with the lugs 39 lying in the longitudinal grooves 3.8, the arm 43 bears against the cam faces 45 so that when the gun is fired and the arm 43 moves in the, direction of the barrel or ring chamber thereof it drives both the bolt and ring pin in the direction of the barrel until the bolt abuts the end of the barrel with the lugs 39 aligning with the grooves 40. The arm bearing against the cam faces 45 during this movement of the bolt besides driving the bolt into firing position it has a tendency to turn or rotate the bolt and as the lugs align with the grooves 40 the bolt rotates a limited distance with the arm 43 and ring pin continuing a sliding movement in the direction of the barrel or firing chamber thereof so that the pointed end of the firing ypin will pass through the aperture 1 and strike the cap of the shell with sufficient force to bring about the explosion of the cap for the purpose of igniting the powder of the shell. On the sliding movement of the arm 43` in a reverse direction or in a direction to cock the bolt and firing pin, said arm and firing pin first slide relative to the bolt until the cam faces 46 are engaged by the arm and the latter bearing with force against said cam faces rotates the bolt 5 in a reverse direction to bring the lugs 39 again into the longitudinal grooves '38 whence said bolt may return to a cocked position along with the firing pin by the influence of said arm 43.

As heretofore stated, the lowermost shell ofl the magazine partially extends into the chamber 4 so that the bolt on leaving a cocked position will engage with the shell and impart endwise y accises' 3 the shell engages with'inclined faces 41 and 48 formed on the walls of the chamber and the end of the gun barrel which has the firing so that said shell will be guided into the firing chamberA in advance of the bolt 5. The end'of the bolt stated, the bolt 5 reaches ring position inf advance of the ring pin so that the shell will be properly positioned in the firing chamber before which is positioned a coil spring 53. The dog includes a body of elongated. formation having one end shaped to form a tongue 54 to engage the groove of the cap of the shell while the opposite end' is reduced to form a plunger 55 slidably received in the chamber 52 and also presents a shoulder 56 for the spring 53 to bear against. Lugs 51 are `formed on the body of the dog and are received in a groove 58 fomed in the bolt 5 and intersecting and arranged at rightangles to the groove 5I. The lugs 51 are provided with beveled faces 59 to contact with undercut faces 58 formed in walls of the grooves 58, the spring 53 acting to keep the faces 59 in engagement 'with the faces 80. The opposite wall of the groove 58 from the faces 88 is beveled, as shown at 8l, which will permit the dog to have a limited sliding movement endwise of the bolt 5 against the action of the spring 53 and also permit the dog to'move slightly out of the groove 5| for the purpose of permitting the end 54 to ride over the cap of the shell and enter the groove ofsaid cap. The dog engaging the shell as described will extract the shell from the firing chamber as the bolt moves towards cocked position, it being understood that the extraction of the shellV takes place after the firing thereof. After the bolt has completed a portion of its movement towards a cocked position an ejector lever 82 engages with the cap end of the shell and with the continued movement of the bolt towards a cocked position the shell is caused to l swing and release itself from the dog and seat and disengage from the-gun by way of'the discharge slot 31 provided therefor, as clearly shown in Figures '7 and 8 of the drawings. The ejector lever is supported intermediate its ends by the pivot which supports the lever 3|. One end ofthe ejector lever engages with the outer face of the bolt during the latters movement towards cocked position causing the opposite end of the lever to move through a slot 94 in the bolt to engage with the cap end of the shell. The slot 94 communicates with the seat 49.

The plunger 44 of the combined i'lring and cocking mechanism slides in a chamber 65 provided in the gun case or frame. One end of this chamber is open to the atmosphere and has extending therein for a short distance' a nipple 65, the passage 81 of which communicates with a passage 68 leading to the barrel of the gun in advance of the firing chamber so that a portion of the ring charge may enter the nipple and exhaust into a cylinder 89 formed in one end of the plunger. The explosive force impinging against the inner end -of the cylinder drives the plunger rearwardly with respect to the gun and as the arm 43 is carried by the plunger it will move the bolt and firing pin into cocked position and as the bolt and ring pin reach the cocked position a sear 'I8 engages in a notch 1| of the plunger. The plunger moving in the direction desc bed compresses a ring spring 12 of the coil type. The spring 12 is mounted on a rod A-13 between a wall 14 of the gun case or frame and the plunger. The plunger is chambered, as shown at 15, to permit a portion of the rod 13 and the spring to lie within the plunger, the rod at its inner end carrying ahead 16 which abuts with the inner end of the chamber 15 being held in engagement therewith by the influence of the ring spring 12. The rod extends through the wall 14 of the gun case or frame so as to be slidably supported thereby and in turn aid in slidably supporting the plunger. It is to be understood that when the plunger is f reed by the se'ar 10 it is driven forwardly of the` gun carrying therewith the bolt 5 and ring pin by the firing spring 12.

The sear l0 is pivotally and slidably mounted, as shown at 11, and one end of the sear has a tongue or projection 18 to engage with a head 19 of a trigger 80. The opposite end of the sear has a head 8| shaped to provide oppositely arranged shoulders 82 and 83. The shoulder 83 engages in the notch of the plunger while the shoulder 82 rides upon a cam 84 carried by Sa shaft 85 journaied to the gun case or frame and whichis provided with angularly related faces 85 engaged by oneend of a leaf spring 81. The cam shaft extends outwardly ofthe gun case or frame and is equipped with a finger piece 88 whereby the cam 88 may be moved intodifferent positions and retained in said positions against accidental movement by the end /of the spring 81 bearing against the angulary related faces 86. A coil spring 89bears against the head 8| of the sear and acts to position the shoulder 83 to engage in the notch of the plunger 84. A trigger guard 9|"is secured to the gun case or frame and includes a hand grip 92 and is provided with a seat 93 for the spring 81, the latter having one end pivotally connected to the head 19 of the trigger 80. The trigger extends into the guard 9| inthe usual manner and the head 19 thereof is provided with a shoulder 94. 'The spring 89 besides acting to position the shoulder 83 of the sear into the notch of theplunger 44 also imparts an endwise movement to the sear in a direction rearwardly with respect to the gun. The cam 84 when in one position will retain the i shoulder 83 in the notch of the plunger and preslide the 'sear forwardly a limited distance so that the shoulder-18 will be disposed over the shoulder 94 of the trigger whereby upon moving the trigger into ring position the scar will be disengaged from the plunger and permit the firing of thegun to be automatic and which operation will continue as -long as shells are received in the firing chamber. A third position of the cam, as

shown in Figure 13, will permit the spring 89 to shift thel sear endwise rearwardly of the gun so that thetrigger must be pulled rearwardly and 'and is adapted to align with the chamber d when said plunger moves into position for cooking the bolt and ring pin so that any particles of `foreign matter which may accumulate within the chamber may escape therefrom by said cutaway portion 95 t'o obviate any possibility of foreign^ matter accumulating to an extent that it would interfere with the operation of the various parts operating in said chamber li. These foreign particles may come from dirt on the shells or chippings from the shell casing.

Should for any reason the automatic recocking of the gun fail, a hand piece 96 is connected to the plunger and operates through a slot in the gun case or frame whereby the plunger may be moved rearwardly with respect to the gun to position the bolt and ring pin in cocked position.

Having described the invention, I claim:

1. A rearm including a gun frame and a barrel removably mounted thereto, said barrel and frame having tapering grooves to align when the barrel is mounted to the frame, a Wedge to enter said groove, a shoulder on the frame, a lever pivotally and slidably secured to the wedge. a shoulder on the pivoted end of the lever to engage the first-named shoulder when said lever occupies one of its positions, and a cam face on the pivoted endof said lever to engage the frame by said lever moving from the stated position to a second position to urge the wedge out of the grooves.

2. A iirearm including a gun frame and a barrel removably mounted thereto, said barreland frame having tapering grooves to align when' the barrel is mounted to the frame, a Wedge to enter said grooves, a shoulder on the frame, a lever pivotally and slidably secured to the wedge, a shoulder on the pivoted end of the levento engage the first-named shoulder when said lever occupies one of its positions, a cam face on the pivoted end of said lever to engage the frame by said lever moving from the stated position to a second position to urge the wedge out of the grooves, and a releasable securing means -between said lever and the frame to hold the lever in the rst-named position.

3. A firearm including a gun frame and a barrel removably mounted thereto, said barrel and frame having tapering grooves to align when the barrel is mounted to the frame, a wedge to enter said grooves, 'a shoulder on the frame, a lever pivotallyand slidably secured to the Wedge, a shoulder on the pivoted end of the lever to engage the flrst-named shoulder when said lever occupies one of its positions, a cam face on the pivoted end of said lever to engage the frame by said lever moving from the stated position to a second position to urge the wedge out of the grooves, a keeper on the frame, and a latch movably mounted on the lever to engage with the keeper for holding said lever in the iirst-named position.

4. A rea'rm including a gun frame and a barrel removably mounted thereto, said barrel and frame having tapering grooves to align when the barrel is mounted to the frame, a wedge to enter said grooves, a shoulder on the frame, a lever pivotally and slidably secured to the Wedge, a shoulder on the pivoted end of the lever to engage the rst-named shoulder when said lever occupies one of its positions, a cam face on the pivoted end of said lever to engage the frame by said lever moving from the stated position to a. second position to urge thewedge out of the grooves, a keeper on the frame, a latch movably mounted on the lever to engage with the keeper for holdling said lever in the first-named position, a' leaf spring carried by the lever and having one Aend bearing against the wedge to act to urge the wedge into the grooves during the time the lever'is occupying the iirst-named position.

5. A firearm including a gun frame and a barrel removably mounted thereto, said barrel and frame having tapering grooves to align when the barrel is mounted to the frame, a wedge to enter said grooves, a shoulder on the frame, a lever pivotally and slidably secured to the wedge, a shoulder on the pivoted end of the lever to engage the first-named shoulder when said lever occupiesrone of its positions, a cam face on the pivoted end of said lever to engage the frame by said lever moving from the stated position to a second position to urge the wedge out of the grooves, a keeper on the frame, a latch movably mounted on the lever to engage with the keeper for holding said lever in the first-named position, a leaf spring carried by the leverand having one end bearing against the wedge to act to urge the wedge into the grooves during the time the lever is occupying the rst-named position, said spring having one end offset to engage the latch acting to retain said latch in engagement with the keeper and 4capable of iiexing to permit manual disengagement of the latch from the keeper.

RAFAEL MENDOZA. 

